PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

Analog and Digital Filters 639

MATLAB Solution

% Script file: filter _ wind

format long

hnk = fir1(64,.4,kaiser(65,3.5));

[h1,w1] = freqz(hnk,1,256);

magk = 20*log10(abs(h1));

subplot(3,2,1)

plot(w1,magk)

title(‘Filter using kaiser win.’)

ylabel(‘gain in db’)

subplot(3,2,2)

hnhan = fir1(64,.4,hanning(65));

[h2,w2] = freqz(hnhan,1,256);

maghan = 20*log10(abs(h2));

plot(w2,maghan)

title(‘Filter using hanning win.’)

ylabel(‘gain in db’)

subplot(3,2,3)

hnbla = fir1(64,.4,blackman(65));

[h3,w3] = freqz(hnbla,1,256);

magblac=20*log10(abs(h3));

plot(w3,magblac)

title(‘Filter using blackman win.’)

ylabel(‘gain in db’)

subplot(3,2,4)

% hamming window is the default

FIGURE 6.63

Filter’s plots of Example 6.13.

4

[Impulse sequence h(n)] versus n

2

0

0510

time n n

15

Amplitude^2

 4

 6

[coeff. a1(n)] versus n

10

5

0

0 2 46

Amplitude

 5

 10

01

12

Real part

Imaginary part

zero-pole plot

1

0.5

0.5

 1

 1

0

20

10

0

 10

 20

 30

 4  2024

W

H1(W) versus W

Amplitude

time index n Index n